ThreadPoolExecutor 线程池参数详解，执行流程

news2024/10/6 22:30:45

线程池的使用:

    public static void main(String[] args) {
        ThreadFactory sThreadFactory = new ThreadFactory() {
            private final AtomicInteger mCount = new AtomicInteger(1);

            @Override
            public Thread newThread(Runnable r) {
                int andIncrement = mCount.getAndIncrement();
                return new Thread(r, "Thread # " + andIncrement);
            }
        };

        Runnable runnable = new Runnable() {
            @Override
            public void run() {
                try {
                    Thread.sleep(1000);
                    System.out.println(Thread.currentThread().getName() + "完成任务");
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
        };

        ThreadPoolExecutor threadPoolExecutor = new ThreadPoolExecutor(2, 10,
                200L, TimeUnit.MILLISECONDS, new LinkedBlockingDeque<>(1), sThreadFactory, new ThreadPoolExecutor.DiscardOldestPolicy());

        for (int i = 0; i < 200; i++) {
            threadPoolExecutor.execute(runnable);
        }
    }

运行后：

ThreadPoolExecutor构造函数详解：

public ThreadPoolExecutor(int corePoolSize,
                              int maximumPoolSize,
                              long keepAliveTime,
                              TimeUnit unit,
                              BlockingQueue<Runnable> workQueue,
                              ThreadFactory threadFactory,
                              RejectedExecutionHandler handler)

corePoolSize：核心线程数，也就是这个线程池一创建就自带多少个线程

maximumPoolSize：最大线程数，就是这个线程池最多能容纳多少个线程

keepAliveTime：设置线程空闲了多长时间后被回收

unit ：第三个参数的时间单位

workQueue：设置加入的任务多过corePoolSize时加入的阻塞队列

threadFactory：线程工厂。一般来说就是给线程改个名

handler：拒绝策略。当加入的任务太多，线程池和阻塞队列都塞满的情况下该怎么办

拒绝策略可选：

①ThreadPoolExecutor.AbortPolicy：直接抛出异常

②ThreadPoolExecutor.CallerRunsPolicy：让调用线程池的自己执行任务

③ThreadPoolExecutor.DiscardOldestPolicy：删除老任务，让新任务进来（渣男行为）

④ThreadPoolExecutor.DiscardPolicy：删除新任务（中国好男人）